1 62 THE SAPROLEGNIACEAE 



l4-29ti, thick, average about 22[ji, eccentric as in the typical form. An- 

 theridia present on all oogonia. The plant was cultivated for a short 

 time on ants and bits of boiled corn grain but grew poorly and soon died 

 out. It may be best to consider it a parasitic variety of the species. 



Our typical form produces oogonia very sparingly. A culture was 

 kept going in the laboratory for four months, on different media, be- 

 fore any oogonia were produced. They have appeared several times: — 

 on ants in distilled water, on mushroom grubs in distilled water, and 

 most promptly and abundantly on the protein (horny) part of corn 

 endosperm that had been boiled for a few minutes. In each case they 

 have appeared only after the cultures were several weeks old. The 

 cultures are rather hardy and will last for some time, but will not go 

 through the summer without transfer. 



The eggs of our plant run smaller than deBary's measurements, 

 which are 27-33^1. Some of the spores are often left in the sporangia, 

 and sprout there into hyphae (pi. 55, fig. 2). 



Dr. Pieters writes (unpublished notes) that "oogonia developed when 

 a mycelium was transferred from 1% peptone to 0.05% haemoglobin, 

 July 24, 1914. Antheridia were abundant and wrapped about the 

 oogonia; no eggs were formed." 



On this species Kasanowsky ('11) has published a good paper show- 

 ing that fertilization occurs. His results are briefly as follows: 



The young oogonium is filled with plasma and contains a large 

 number of nuclei and a large central vacuole; a number of the original 

 nuclei go to pieces, others divide simultaneously by mytosis; all the 

 nuclei from this division go to pieces except one which becomes the 

 egg-nucleus; there is now formed a dense mass with radiating strands 

 called the coenocentrum, comparable to the similar body in the Pero- 

 nosporaceae, near which lies the egg nucleus which increases in size. 

 The antheridia contain 4-6 nuclei, which divide mytotically and then 

 degenerate with one exception; this male nucleus is then discharged into 

 the egg through a fertilizing tube, along with the protoplasm of the an- 

 theridium, and fuses with the egg nucleus; fat is formed in small particles 

 which fuse to form larger ones which finally unite to form a single large 

 drop with a distinct membrane and probably also an internal ground- 

 work (stroma) of its own. The ripe egg is uninucleate, with the large 

 fat drop usually in the center. After six months the egg sprouts to a 

 tube which soon branches. 



For other cytological data see Dangeard ('90), p. 113, pi. 6, figs. 6-17. 



